Prized Muga silkworm’s mitochondrial genome decoded

doi:10.1038/nindia.2017.144 Published online 24 November 2017

The researchers (standing from left): Vimal, Deepika Singh, Hasnahana Chetia, Pragya Sharma, Debojyoti Kabiraj & (seated) Utpal Bora.
Indian researchers have moved a step closer to understanding the evolution of the prized Muga silkworm of Assam by sequencing the mitochondrial genome of the insect1. Mitochondria are intracellular organelle with their own set of genes that regulate energy metabolism inside cells.

The sequencing will help identify genetic markers or specific gene sequences that reveal the identity of an insect such as the silkworm.

Muga is among the most expensive commercially available silk fibres and is intricately related to the culture of the north-east Indian state of Assam. In recent years, rampant use of pesticides in the state's tea gardens and adjoining agricultural fields has greatly affected the growth of Muga silkworms, reducing their silk production.

The researchers, led by Utpal Bora, from the Indian Institute of Technology, Guwahati, Central Muga Eri Research & Training Institute, Jorhat and Gauhati University, Guwahati found that the silkworm’s mitochondrial genome has 37 genes exclusively passed down from the mother to the offspring. They identified mutations in a few key mitochondrial genes.

One such mutated gene is atp8 which encodes an enzyme that helps synthesise adenosine triphosphate (ATP), an energy-carrying molecule from adenosine diphosphate. “Being a silk-producing insect, the Muga silkworm's requirement of energy for silk production may have contributed to the evolution of the atp8 gene sequence,” Bora explains.

He says the the genes that encode proteins involved in ATP synthesis and other vital biochemical pathways are now known. “Armed with this knowledge, it is easier to pin down the dynamics of energy metabolism in various cellular processes that eventually churn out silk fibre.